He reads through the message several times, seemingly deep in thought.
It leaves a sinking feeling in his stomach, because even if the message is horribly rude and makes Looker uncomfortable, it is probably true on some level.
That is why it makes him uncomfortable - all those thoughts haunts him, even if the agent does his best to keep them subdued. When you work for Interpol, it is never a good idea to actually enjoy the company of criminals.
He has grown a little fond of those two lately, even if he does not agree in the slightest with their ideas or goals.